Las Vegas is the most populous city in the U.S. state of Nevada and serves as the county seat of Clark County. Situated in a basin on the floor of the Mojave Desert, it is surrounded by mountain ranges that act as barriers to moisture from the surrounding area. The city lies within the Las Vegas Valley, which functions as the leading financial, commercial, and cultural center for the state. Its location in this arid region supports extensive vegetation near natural water sources known as the Las Vegas Springs.

The area was first encountered by non-Native Americans in 1829 when Mexican trader Antonio Armijo led a group along the Old Spanish Trail. The city was founded in 1905 when land adjacent to Union Pacific Railroad tracks was auctioned, and it was officially incorporated as a city in 1911. A pivotal moment occurred in 1931 when Nevada legalized casino gambling and reduced divorce residency requirements, while the construction of Hoover Dam brought an influx of workers that helped the city avoid economic calamity during the Great Depression.

Internationally renowned as a major resort city, Las Vegas is famous for its gambling, shopping, fine dining, entertainment, and nightlife. Most venues are located in downtown Las Vegas or on the Las Vegas Strip, which lies outside city limits in the unincorporated towns of Paradise and Winchester. The city bills itself as the Entertainment Capital of the World and is known for luxurious casino-hotels. Its tolerance for adult entertainment has earned it the nickname Sin City, influencing its portrayal in films and literature.

The city attracts over 40.8 million visitors annually, ranking among the world's top tourist destinations and the third most popular U.S. destination for business conventions. Key sites include the Fremont Street Experience, a canopied five-block area in downtown featuring LED lights and sound shows, and the historic Old Mormon Fort. The Strip features elaborate fountain displays, circuses, stage shows, and nightclubs, while the northern end is marked by the Stratosphere Tower, drawing visitors with its array of amusements and attractions.

Las Vegas had a population of 641,903 as of the 2020 census, making it the 24th-most populous city in the United States. The climate is subtropical hot desert, characterized by long, extremely hot summers and short winters with mild days. July is the hottest month, with an average daytime high of 104.5 °F, while rainfall is scarce at an average of 4.2 inches per year. The city benefits from abundant sunshine, averaging 310 sunny days annually, and serves as a global leader in the hospitality industry.